Once great but now dated
I think the simplest way I can describe my feelings about playing through Call of Duty 2 in 2020 is that while this game was definitely impressive back in its day, it doesn't come across as anything special today. The one thing this game sometimes does very well - and a big reason why this game was a success in its day - is that it can simulate the feeling of being one small piece of a much larger conflict very well.
Obviously, you'll be walking through various European, Russian, and African battlefields killing Nazis by the hundreds. But things are constantly happening to your character as well. Explosions are constant and everywhere. Tanks will roll up and lay waste to a whole squad of soldiers. You'll desperately hang on and try to control a small bunker against an overwhelming force, only to be saved at the last minute by a bomber run. The missions are for the most part tightly scripted, maybe to a fault, but the game takes advantage of controlling the player experience so heavily by keeping the pace and excitement cranked up. This is a trick Infinity Ward had definitely already started to master here, and it will fully blossom in their next game.
Everything I described in the last paragraph? That's what stood out to me about Call of Duty 2 now. The rest of it? Well...as I said, it's showing its age. As a 2005 launch Xbox 360 game, the graphics are functional but not a whole lot more. The subject matter also doesn't lend itself much to artistic flair, and the game's sense of style could be described as clinical. The tight scripting does create exciting moments, but it can also lead to weird moments where a bunch of Nazis run straight in front of you towards the spot the game is telling them they need to be like actors rushing to hit their marks. Also, this might say more about 2020 than CoD 2, but the lack of systems reallydates this game more than anything else. No collectables, no unlocks, no dialogue trees. Just corridors and Nazis with guns.
CoD 2 also doesn't have much in the way of a main story. While there are some characters that will show up in multiple missions, the campaign mostly comes across as a series of only loosely-connected battles. There are some good set-piece moments, but it all wraps up kind of anti-climatically. The two tank missions are bad, but they are mercifully short. For whatever it's worth, I found the final British mission and the American campaign to be the highlights of the game, combining good environment design with exciting encounters. The first few parts of the British campaign, on the other hand, I thought started to get a bit monotonous.
So, like I said at the top, this game doesn't really come across as anything special today. The strong fundamentals of the gun play and the encounter design means its still a solid 8 hour romp through the campaign. And it's not hard to draw a line from here to Modern Warfare. Infinity Ward had the basics covered here; once they were able to free themselves from this stifling setting and take advantage of a few more years experience with this generation of consoles, it's easy to see how they were able to build on this to create a genre-defining game.